The present invention is directed to a prestressed concrete railroad tie having a monolithic tie body and to a method of fabricating the tie.
Railroad ties constructed as a monolithic tie body including two end members carrying the attachment parts for the rails and a central member interconnecting the end members are made of reinforced concrete. The advantage of such tie members is that the abutting support forces of the ballast beds are concentrated in the region about the axes of the rails. As a result, there is a reduction in the bending moments, particularly in the slender central member of the tie affording a lower reinforcing steel requirement with a corresponding reduction in costs. The more costly fabrication of the concrete reinforcement and the danger or crack formations in the tie member when subjected to oscillating loads are disadvantages of this type of tie and has greatly reduced the practical significance of such ties.
In prestressed concrete ties, the tie body has, for the most part, a prismatic shape. As a result, such ties experience higher bending moments as compared to a tie member with a central slender member or part. Such ties have been accepted because of the simple straight line course of the prestressing elements or tendons. A marked transverse crosssectional reduction in the central part of the tie body has not been possible with prestressed concrete ties, since the position of the individual tendons is fixed initially by the required uniform distribution of the end anchors across the transverse cross-sectional of the tie ends